Brain scan studies have shown certain characteristic alterations that are associated with aging. The hippocampus, a key memory center located in the medial temporal lobe (beneath the temples), gradually shrinks.

In addition, PET scans indicate that aging neurons are firing less in brain areas that control thinking and memory.

Using functional MRI scanning to track mental activities, scientists have shown that with age, our brains have to work harder when we want to learn and recall new information.

In people who experience mild memory slips, heightened activity can be seen in brain regions that control memory function during the process of trying to retrieve memories.

However, when these people are taught simple memory techniques, their recall abilities improve dramatically and the scans then reveal less activity in those brain regions, indicating a higher level of brain efficiency.

The effect is similar to what is observed from physical training.

When we first start working out at the gym, the exercises can be exhausting. But with practice, we can lift more weight and work out longer while exerting less energy.